Welcome to HVAC-Talk.com, a non-DIY site and the ultimate Source for HVAC Information & Knowledge Sharing for the industry professional! Here you can join over 150,000 HVAC Professionals & enthusiasts from around the world discussing all things related to HVAC/R. You are currently viewing as a NON-REGISTERED guest which gives you limited access to view discussions

To gain full access to our forums you must register; for a free account. As a registered Guest you will be able to:

Participate in over 40 different forums and search/browse from nearly 3 million posts.

You should try being in the awkward position of calling your boss 3 times in one summer to tell him his SON misdiagnosed a compressor and have that same son hate you for it. I could go on and on with all the times this happened.

Many moons ago when I was still gourd green I found a compressor contactor with a bad coil. Found it within minutes on a Carrier package unit. Thought to self oh yeah I got this! This heating and air gig is cake! All that could be made out on the coil was a 2. No problem thought, got this on the truck. Replaced the contactor and turned the machine on. Very briefly after the contactor pulled in is when I learned the difference between 24 volt controls and 208 ! Luckily I had stepped back from the machine and when the contactor exploded none of the shrapnel hit me. Always Always Always make sure of your voltage and if your company has arc flash protection for you use it!

Went to jump out a water source heat pump today using R to Y1 (the maintenance guys would of had to start it using their automated system, and they typically don't want to be bothered). It still wouldn't energize so I decided to take the jumper off (with 460 volts still flowing through). One side of my beautiful little magnetic jumper wire (those $10 yellow ones) popped off and instantly stuck to some other metal, apparently grounding the transformer. Sparks and smoke...kicked the breaker....so I ended up bothering the maintenance guys anyway (didn't know where the breaker box was).

Hope this makes your day seem a little less worse.

I'm still trying to figure out how you had 460 volts flowing through your jumper by jumping out R to Y1. Austin, can you elaborate on that?

I've seen many 24 volt secondary's grounded (ie. weedeater or dog chewing up 24 volt t-stat wire at condensing unit), but have never in my life seen that trip a breaker or cause a significant spark that would cause smoke.....

I've seen many 24 volt secondary's grounded (ie. weedeater or dog chewing up 24 volt t-stat wire at condensing unit), but have never in my life seen that trip a breaker or cause a significant spark that would cause smoke.....

But if a spring type gator clip being used on the secondary popped off and headed anywhere close to the contactor, you would flinch just as anyone of us would. I'm thinking that's what happened here. He was diagnosing with the unit energized and his little mag clips popped off and made contact with the primary load circuit at some point.

Those mag jumpers are an accident waiting to happen. You had a worst case scenario, but even if the thing had stuck to cabinet or the c terminal with low voltage on the other end you would have had a blown fuse or transformer (speaking from experience)
Save those for recessed terminals like on a pcb connector and be very careful connecting them. If there is anything to grab, I'd stick to alligator clips, as much of a pain as they can be.
-another tech slowly losing his green sheen